U.S. patent application number 17/089092 was filed with the patent office on 2021-05-13 for electrode cutting instrument.
This patent application is currently assigned to Sion Power Corporation. The applicant listed for this patent is Sion Power Corporation. Invention is credited to David Child, Steven M. Kidder, Manuel Perez, Urs Schoop, Troy Shannon.
Application Number | 20210138673 17/089092 |
Document ID | / |
Family ID | 1000005356573 |
Filed Date | 2021-05-13 |
![](/patent/app/20210138673/US20210138673A1-20210513\US20210138673A1-2021051)
United States Patent
Application |
20210138673 |
Kind Code |
A1 |
Shannon; Troy ; et
al. |
May 13, 2021 |
ELECTRODE CUTTING INSTRUMENT
Abstract
Systems and methods related to cutting electrodes (e.g. lithium
metal) and electrode precursors are generally provided. The
electrodes or electrode precursors may involve, for example, a
lithium metal electrode or a lithium composite electrode, e.g., for
use in an electrochemical cell or battery.
Inventors: |
Shannon; Troy; (Tucson,
AZ) ; Schoop; Urs; (Tucson, AZ) ; Child;
David; (Tucson, AZ) ; Kidder; Steven M.;
(Tucson, AZ) ; Perez; Manuel; (Tucson,
AZ) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Sion Power Corporation |
Tucson |
AZ |
US |
|
|
Assignee: |
Sion Power Corporation
Tucson
AZ
|
Family ID: |
1000005356573 |
Appl. No.: |
17/089092 |
Filed: |
November 4, 2020 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
62932475 |
Nov 7, 2019 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B26D 2001/006 20130101;
B26D 2001/0053 20130101; H01M 10/052 20130101; H01M 4/382 20130101;
H01M 4/04 20130101; B26F 1/40 20130101; H01M 4/1395 20130101; B26D
7/1863 20130101; B26D 1/0006 20130101 |
International
Class: |
B26D 1/00 20060101
B26D001/00; H01M 10/052 20060101 H01M010/052; H01M 4/1395 20060101
H01M004/1395; H01M 4/38 20060101 H01M004/38; H01M 4/04 20060101
H01M004/04; B26F 1/40 20060101 B26F001/40; B26D 7/18 20060101
B26D007/18 |
Claims
1. A system for cutting a lithium metal layer, comprising: an
asymmetric blade, the asymmetric blade comprising a tip, a first
edge, and a second edge, as shown in a cross-section of the blade;
a first interleaf layer; a second interleaf layer, wherein the
lithium metal layer is positioned between the first interleaf layer
and the second interleaf layer; and a substrate positioned adjacent
to the second interleaf layer.
2. An electrode precursor, comprising: a first interleaf layer; a
second interleaf layer; a lithium metal layer having a
cross-section; and an optional protective layer adjacent the
lithium metal layer, wherein the first and second interleaf layers
are in conformal contact with the lithium metal layer and/or the
optional protective layer, and wherein the first interleaf layer
and the second interleaf layer surround a perimeter of the
cross-section of the lithium metal layer and optional protective
layer.
3. A method for cutting lithium metal, the method comprising:
positioning a layer of the lithium metal between a first interleaf
layer and a second interleaf layer, cutting the lithium metal with
a blade to form a cut lithium metal piece having a cross-section,
wherein the cutting step does not cut through the first interleaf
layer, and adhering the lithium metal to the first interleaf layer
and/or the second interleaf layer such that the first interleaf
layer and second interleaf layer surrounds a perimeter of the
cross-section of the cut lithium metal piece.
4. (canceled)
5. The system of claim 1, wherein the asymmetric blade has a
longitudinal axis perpendicular to the substrate, the longitudinal
axis passing through the tip of the blade as shown in the
cross-section of the blade, and wherein a first angle is formed
between the first edge and the longitudinal axis.
6. The system of claim 1, wherein the asymmetric blade has a
longitudinal axis perpendicular to the substrate, the longitudinal
axis passing through the tip of the blade as shown in the
cross-section of the blade, and wherein a second angle is formed
between the second edge and the longitudinal axis.
7. The system of claim 5, wherein the first angle is less than or
equal to 25 degrees.
8. The system of claim 6, wherein the second angle is less than or
equal to 70 degrees.
9. The system of claim 6, wherein first angle and the second angle
have a sum greater than or equal to 50 and less than or equal to
75.
10. The system of claim 1, wherein a thickness of the lithium metal
layer is greater than or equal to 25 microns.
11. The system of claim 1, wherein a thickness of the first
interleaf layer is less than or equal to 250 microns.
12. The system of claim 1, wherein a thickness of the first
interleaf layer is greater than or equal to 0.5 microns.
13-14. (canceled)
15. The system of claim 1, wherein the first interleaf layer
comprises a polymer.
16. (canceled)
17. The system of claim 1, wherein the second interleaf layer
comprises a polymer.
18-21. (canceled)
22. The system of claim 1, further comprising an additional
layer.
23. The system of claim 22, wherein the additional layer comprises
a release layer.
24. The system of claim 22, wherein the additional layer comprises
an electrode layer.
25. The method of claim 3, further comprising removing the first
interleaf layer from the lithium metal.
26. The method of claim 3, further comprising lifting the lithium
metal from the second interleaf layer.
27. The method of claim 26, wherein the lifting step is performed
with a vacuum apparatus.
28. The method of claim 26, wherein the lifting step occurs within
30 seconds or less of the cutting step.
29-31. (canceled)
Description
RELATED APPLICATIONS
[0001] This application claims priority under 35 U.S.C. .sctn.
119(e) to U.S. Provisional Application No. 62/932,475, filed Nov.
7, 2019, and entitled "ELECTRODE CUTTING INSTRUMENT," which is
incorporated herein by reference in its entirety for all
purposes.
TECHNICAL FIELD
[0002] Systems and methods for cutting electrodes and electrode
precursors, including lithium metal, are generally described.
SUMMARY
[0003] Systems and methods for cutting electrodes and electrode
precursors, including lithium metal, are generally described. The
subject matter of the present invention involves, in some cases,
interrelated products, alternative solutions to a particular
problem, and/or a plurality of different uses of one or more
systems and/or articles.
[0004] In one aspect, a system for cutting a lithium metal layer is
described. The system comprises an asymmetric blade, the asymmetric
blade comprising a tip, a first edge, and a second edge, as shown
in a cross-section of the blade. The system also comprises a first
interleaf layer and a second interleaf layer, wherein the lithium
metal layer is positioned between the first interleaf layer and the
second interleaf layer. The system also comprises a substrate
positioned adjacent to the second interleaf layer.
[0005] In one embodiment, an electrode precursor is described. The
electrode precursor comprises a first interleaf layer, a second
interleaf layer, a lithium metal layer having a cross-section, and
an optional protective layer adjacent the lithium metal layer. The
first and second interleaf layers are in conformal contact with the
lithium metal layer and/or the optional protective layer. The first
interleaf layer and the second interleaf layer surround a perimeter
of the cross-section of the lithium metal layer and optional
protective layer.
[0006] In another embodiment, a method for cutting a lithium metal
layer is provided. The method comprises positioning a layer of the
lithium metal between a first interleaf layer and a second
interleaf layer; cutting the lithium metal with a blade to form a
cut lithium metal piece having a cross-section, wherein the cutting
step does not cut through the first interleaf layer. The method
also comprises adhering the lithium metal to the first interleaf
layer and/or the second interleaf layer such that the first
interleaf layer and second interleaf layer surrounds a perimeter of
the cross-section of the cut lithium metal piece.
[0007] In yet another embodiment, a method for cutting lithium
metal is provided. The method comprises positioning the lithium
metal between a first interleaf layer and a second interleaf layer;
cutting the lithium metal and the first interleaf layer with an
asymmetric blade; and adhering the first interleaf layer to the
lithium metal. Other advantages and novel features of the present
invention will become apparent from the following detailed
description of various non-limiting embodiments of the invention
when considered in conjunction with the accompanying figures. In
cases where the present specification and a document incorporated
by reference include conflicting and/or inconsistent disclosure,
the present specification shall control.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] Non-limiting embodiments of the present invention will be
described by way of example with reference to the accompanying
figures, which are schematic and are not intended to be drawn to
scale. In the figures, each identical or nearly identical component
illustrated is typically represented by a single numeral. For
purposes of clarity, not every component is labeled in every
figure, nor is every component of each embodiment of the invention
shown where illustration is not necessary to allow those of
ordinary skill in the art to understand the invention. In the
figures:
[0009] FIGS. 1A-1G depict systems and a process for cutting lithium
metal, according to one set of embodiments;
[0010] FIG. 2A is a schematic diagram of an asymmetric blade for
cutting lithium metal, according to some embodiments;
[0011] FIG. 2B depicts an asymmetric blade for cutting lithium
metal, according to some embodiments;
[0012] FIG. 2C depicts an asymmetric blade with more than two
cutting edges, according to some embodiments;
[0013] FIGS. 2D-2F depict an asymmetric blade with two tips cutting
a layer of lithium metal, according to some embodiments;
[0014] FIGS. 3A-3B illustrate a system and method for cutting
through a first interleaf layer, according to some embodiments;
[0015] FIGS. 3C-3D illustrate a system and method for cutting
through a first interleaf layer and a protective layer, according
to some embodiments;
[0016] FIG. 4 is a schematic of an electrode precursor, according
to some embodiments;
[0017] FIGS. 5A-5G show a system and a process for cutting a layer
of lithium metal using two asymmetric blades that may be part of a
die, according to one set of embodiments;
[0018] FIGS. 6A-6C depict an electrode assembly with a release
layer, according to some embodiments; and
[0019] FIG. 7 is a photographic image of a die comprising an
asymmetric edge for cutting a layer of lithium metal, according to
one set of embodiments.
DETAILED DESCRIPTION
[0020] Systems and methods related to cutting electrodes (e.g.,
lithium metal) and electrode precursors are generally provided. The
electrodes or electrode precursors may involve, for example, a
lithium metal electrode or a lithium composite electrode, e.g., for
use in an electrochemical cell or battery.
[0021] Lithium metal may be purchased commercially as a solid
suspension in oil or as a foil. It can also be deposited on to a
substrate using a variety of techniques, such as vapor deposition,
vacuum deposition, or molecular beam epitaxy techniques. In order
to fit the dimensions required for its intended use (e.g., as an
electrode in an electrochemical cell, a battery), the lithium may
require cutting.
[0022] However, cutting lithium metal may present several
challenges. For example, lithium metal is soft and malleable such
that when metallic lithium is cut, it may be sticky and adhere to
the cutting instrument (e.g., a knife, a blade) when used to cut
metallic elemental lithium. This can present difficulties when
cutting multiple pieces of lithium metal in succession because
cleaning the blade in between each cut can slow down the process of
preparing electrodes and may also dull the blade. Certain existing
lithium metal cutting systems attempt to circumvent this issue by
positioning the lithium metal between interleafs so that the blade
does not directly contact the blade. However, even in such existing
systems, lithium may still undesirably adhere to the interleafs,
making subsequent removal of the lithium from the interleafs
difficult.
[0023] Certain existing systems use a symmetric blade to cut
lithium metal. However, as described herein, the Inventors have
recognized and appreciated that use of an asymmetric blade may
provide several advantages over certain existing systems using a
symmetric blade. For example, an asymmetric blade may provide a
cleaner cut when compared to the use of a symmetric blade. A
cleaner cut reduces the amount of lithium metal that may adhere to
the blade or to an interleaf layer after cutting. Additionally, a
cleaner cut, as provided by an asymmetric blade, may allow more
multiple, repeated cuts in succession while reducing the amount of
lithium metal waste produced when compared using a symmetric
blade.
[0024] In some embodiments, an additional advantage is that the
asymmetric blade may cut the lithium metal layer without cutting an
interleaf layer (e.g., a first interlayer, a second interleaf layer
described below) that may be present above and/or below the lithium
metal layer. In this way, a layer of lithium metal may be cut
without the asymmetric blade making direct contact with lithium
metal. As yet another advantage, the asymmetric blade may cause the
lithium to adhere temporarily (e.g., stake) to the interleaf
layer(s), which provides certain benefits. For example, adhering
the cut lithium metal to a bottom interleaf layer (e.g., a second
interleaf layer) may advantageously allow for easier removal of a
top interleaf layer, while leaving the cut lithium metal (e.g., a
lithium electrode) adhered to the bottom interleaf layer. This step
may facilitate easier downstream processing when compared to
certain existing lithium metal systems, as described in more detail
below.
[0025] In some embodiments, the asymmetric blade may be configured
into a die cast in the shape of an electrode. When the die is
pressed down onto a layer of lithium metal positioned in below an
interleaf layer (e.g., a top interleaf layer), the layer of lithium
metal may be cut in the shape of the electrode while leaving the
frame (i.e., the portion of the lithium metal not cut into an
electrode) behind. Upon removal of the top interleaf layer from the
cut lithium electrode, the cut electrode may be readily removed
while leaving behind the frame in place on a bottom interleaf
layer.
[0026] A system for cutting a lithium metal layer is illustrated in
FIG. 1. Specifically, FIG. 1A depicts a cross-section of a system
100, a system for cutting a lithium metal layer, prior to cutting
the lithium metal layer. As shown illustratively in this figure, a
layer of lithium metal 105 is positioned between a first interleaf
layer 120 and a second interleaf layer 125. An asymmetric blade 110
is positioned above the first interleaf layer and may be moved
downward toward a substrate 130 along axis 140, which is defined by
a line perpendicular to the substrate passing through the tip of
the asymmetric blade. The lithium metal layer may be positioned
relatively upstream, illustrated by arrow 142, and at least
partially positioned downstream as it is being cut, in the
direction of the location of arrow 144.
[0027] As shown illustratively in FIG. 1B, in some embodiments the
asymmetric blade may be lowered such that it crush cuts the lithium
metal layer 105 into two pieces of lithium metal, lithium metal
piece 105A and lithium metal piece 105B, without cutting the first
interleaf layer 120, because the asymmetric blade does not directly
contact the lithium metal. Due to the asymmetry of the asymmetric
blade, lithium metal piece 105A and lithium metal piece 105B may
have adjacent sides (i.e., two adjacent sides created by cutting
the layer of lithium metal 105) with distinct slopes and/or
distinct angles, as schematically illustrated in the figure. In
some embodiments, the first interleaf layer 120 may adhere (e.g.,
temporarily) to the second interleaf layer 130, as shown
illustratively in FIG. 1B. Lithium metal piece 105A and 105B may be
moved further downstream (e.g., by a conveyer belt) and lithium
metal 105C may be subsequently positioned to be cut by the
asymmetric blade, illustrated in FIGS. 1C-1D. The asymmetric blade
may then be lowered to cut lithium metal 105C into two pieces,
shown illustratively in FIG. 1E.
[0028] As used herein, when a layer is referred to as being "on" or
"adjacent" another layer, it can be directly on or adjacent the
layer, or an intervening layer may also be present. A layer that is
"directly on", "directly adjacent", "in contact with", or "in
conformal contact with" another layer means that no intervening
layer is present. Likewise, a layer that is positioned "between"
two layers may be directly between the two layers such that no
intervening layer is present, or an intervening layer may be
present.
[0029] After being moved further downstream, the first interleaf
layer 120 may be removed from at least a portion of the cut lithium
metal. For example, as shown illustratively in FIG. 1F, lithium
metal piece 105B has had first interleaf layer 120 removed, such
that the first interleaf layer envelops or surrounds lithium metal
piece 105C, but not lithium metal piece 105B. Once the first
interleaf layer has been removed from a lithium metal piece 105B,
the cut lithium metal piece may be removed from the system, shown
illustratively in FIG. 1G.
[0030] As described above, an asymmetric blade may be provided for
cutting the layer of lithium metal, and the use of such an
instrument may provide several advantages, as previously described.
Referring now to FIG. 2A, an asymmetric blade 110 may comprise a
tip 202, a first side 205, and a second side 210. The tip may be
formed by the intersection of a first edge 212 of the blade and a
second edge 214 of the blade, which may form an angle with
longitudinal axis 140 as shown in a cross-section of the blade. As
illustrated in the figure, longitudinal axis 140 is formed by a
line that passes through the tip of the asymmetric blade and the
line is perpendicular to the substrate 130. In this particular
exemplary embodiment shown in FIG. 2A, longitudinal axis 140 is
parallel with the first side 205 and the second side 210; however,
it should be appreciated that other configurations are also
possible, as described in more detail below.
[0031] As illustrated in FIG. 2A, first edge 212 forms a first
angle 220 with respect to longitudinal axis 140. Similarly, second
side 214 forms a second angle 230 with respect to the longitudinal
axis. In some embodiments and as pictured in FIG. 2A, the first
angle and the second angle are not equal, such that the blade is
asymmetric with respect to the first edge and the second edge due
to having different angles (e.g., as shown in a cross-section of
the blade).
[0032] As contrasted with a symmetric blade of certain existing
systems, an asymmetric blade is characterized by having at least
two cutting edges (e.g., a first edge, a second edge) that join at
the tip of the blade at two distinct angles. As is shown and
described above in FIGS. 1-2, the angles of the asymmetric blade
may be defined along a longitudinal axis passing through the tip of
the blade and perpendicular to a substrate positioned below the
tip. The first edge may have a first angle formed at the
longitudinal axis and a second angle defined by the second edge and
the longitudinal axis. The first angle and the second angle are
distinct in order to create asymmetry in the blade, and when the
blade is used in a crush cut (i.e., a cut that completely
penetrates a layer to create two separate pieces), the edges of the
cut pieces will have two different slopes reflecting the geometry
of the asymmetric blade's first angle and second angle, as
illustrated in FIG. 1B. For example, when the first angle is
smaller than the second angle, the resulting cut in the layer
(e.g., a lithium metal layer) will have a steeper slope along the
layer that was cut with the first edge, while the portion of the
layer cut with second edge will have a less steep slope. In some
embodiments, the less steep edge of the asymmetric blade (i.e., the
edge with larger angle) may cause an inner corner of the cut layer
of lithium metal to adhere (e.g., stake) to an interleaf layer.
That is to say, the less steep edge of the asymmetric blade may cut
the lithium metal, in addition to staking the lithium metal to a
certain interleaf layer (e.g., the first interleaf layer and/or the
second interleaf layer). The asymmetric blade may have an interleaf
layer positioned between itself and the lithium metal layer, such
that the asymmetric blade does not come into direct contact with
the lithium metal layer. In some embodiments, the asymmetric blade
may cut the first interleaf layer along with the lithium metal
layer. This feature may be useful when preparing lithium electrodes
to be used as a component for an electrochemical cell or a battery.
For example, when the first interleaf layer comprises a battery
separator material, the asymmetric blade may cut the first
interleaf layer and the lithium metal layer, where the cut first
interleaf layer may serve as a battery separator positioned
adjacent the cut lithium electrode (e.g., for incorporation into an
electrochemical cell).
[0033] In some embodiments, an electrode precursor material is
formed using the asymmetric blade. The asymmetric blade may be
configured to cut the lithium metal layer while leaving the first
interleaf layer uncut by the asymmetric blade. The asymmetric blade
may then cause the first interleaf layer and/or the lithium metal
to adhere to the second interleaf layer by creating a pinch between
the first interleaf layer, the cut lithium metal layer, and the
second interleaf layer. This pinch can then be moved downstream and
the cut process repeated, to create electrode precursor material.
An example of such an electrode precursor is illustrated in FIG. 4
and is described further below.
[0034] FIG. 2B depicts another asymmetric blade in accordance with
some embodiments. In this figure, first side 205 and second side
210 are horizontal, such that longitudinal axis 140 is no longer
parallel with the first side or the second side. However, as
illustrated in the figure, the longitudinal axis 140 is still
defined by being perpendicular to the substrate and passes through
the tip of the asymmetric blade like in FIG. 2A. FIG. 2B
illustrates an embodiment that may be particularly advantageous
when the asymmetric blade is a part of a die, i.e., for die
cutting.
[0035] As mentioned elsewhere herein, in some embodiments, an
asymmetric blade may have more than one tip. Referring now to FIG.
2C, the asymmetric blade has two tips, first tip 240 and second tip
242, a first side 244, and a second side 246. In addition to a
first edge 250 and a second edge 252, the asymmetric blade also
comprises a third edge 254 and a fourth edge 256. Longitudinal axis
140 defines a first angle 260 and a second angle 262, while a
second longitudinal axis 270 defines a third angle 264 and a fourth
angle 266. In such an embodiment, a layer of lithium metal may be
cut such that the portion of the layer of lithium between first tip
240 and second tip 242 is cut to have cut edges that are
complementary to second edge 252 and third edge 254. In some
embodiments, the second angle 262 and the fourth angle 266 are
identical, such that a cut edge of lithium metal cut between first
tip 240 and second tip 242 have identical slopes. Such embodiments
may be advantageous in die cutting, as will be described in more
detail below.
[0036] In some embodiments, the asymmetric blade may comprise more
than two cutting edges, as was described above. Referring now to
FIG. 2D, a system for cutting a layer of lithium metal comprises an
asymmetric blade 200, where the asymmetric blade comprises two tips
and four edges (i.e., two edges for each tip, as shown in a
cross-section of the blade). A layer of lithium metal 276 is
positioned adjacent to substrate 278 and between the first
interleaf layer 272 and the second interleaf layer 274. As shown
illustratively in FIGS. 2D-2E, the asymmetric blade may be lowered
along longitudinal axis 270 so as to cut the layer of lithium metal
276. In such an embodiment comprising an asymmetric blade with two
tips, the layer of lithium metal may be cut into more than two
pieces, as shown illustratively in FIG. 2E, where the layer of
lithium metal 276 is cut into lithium metal piece 276A, lithium
metal piece 276B, and lithium metal piece 276C.
[0037] It is noted that lithium metal piece 276B has cut edges that
correspond to the angles and/or sides of the asymmetric blade 200
(e.g. the second edge, the third edge, the second angle, the third
angle), such that the cut edge of lithium metal piece 276A and
lithium metal piece 276C (which are cut by edges not between the
first tip and the second tip) are distinct in slope when compared
to the cut edges of lithium metal piece 276B (which are cut by
edges between the first tip and the second tip). In some
embodiments, lithium metal piece 276C is a piece that will not be
part of an electrode (e.g., lithium waste) and may be moved
downstream and/or removed from the system, illustratively depicted
in FIG. 2F. In some embodiments, lithium metal piece 276B may form
a component of an electrochemical cell, e.g., as a lithium
electrode. In some embodiments, lithium metal piece 276A may
proceed downstream and continue to be cut by the asymmetric blade.
In some embodiments, the asymmetric blade may stake (i.e., adhere
with a relatively high adhesive affinity) or adhere lithium metal
piece 276B to the second interleaf layer.
[0038] In some embodiments, the asymmetric blade may be configured
such that it cuts the first interleaf layer, in addition to the
lithium metal layer. Cutting the first interleaf layer in addition
to the lithium metal layer leaves a cut layer of the first
interleaf layer adjacent to the cut lithium metal layer. When this
cut interleaf layer is, for example, a battery separator material,
the cut interleaf layer remains adjacent to the lithium metal
electrode (e.g., for incorporation into an electrochemical cell).
Referring now to FIG. 3A, the asymmetric blade 310 has been
positioned such a first angle 314 (e.g., a smaller angle) is now
positioned towards upstream position 342 and a second angle 312
(e.g., a larger angle) is now positioned towards downstream
position 344. Lithium metal 305 is positioned between a first
interleaf layer 320A and a second interleaf layer 330. In some
embodiments, this configuration allows the asymmetric blade to cut
the first interleaf layer. The asymmetric blade may be lowered
towards substrate 340 and may cut the first interleaf layer 320A
into first interleaf layer piece 320B and first interleaf layer
piece 320C. In addition, lithium metal layer 305 may be cut into
lithium metal piece 305A and lithium metal piece 305B. As shown
illustratively in FIG. 3C and FIG. 3D, an optional protective layer
350 may be present adjacent (e.g., directly adjacent) the lithium
metal layer 305. When the asymmetric blade is lowered towards
substrate 340, it may cut the lithium metal, in addition to the
optional protective layer 350, forming protective layer 350A and
protective layer 350B.
[0039] In some embodiments, an electrode precursor may be formed.
As shown illustratively in FIG. 4, an envelope-like structure may
be formed by the asymmetric blade, such as asymmetric blade 410,
whereby the first interleaf layer 410 may conformally contact
lithium metal pieces 405A, 405B, and 405C, and the first interleaf
layer may also remain adhered to second interleaf layer 420.
Together, the first and second interleaf layers may substantially
surround or envelope the cut lithium piece(s).
[0040] In some embodiments, a system for cutting lithium metal
comprises at least two asymmetric blades. The at least two
asymmetric blades may be part of a common die. Such an embodiment
may advantageously produce a cut piece of lithium metal that has
identical cut edges (e.g., edges with the same slope), e.g., around
the perimeter of the cut lithium metal. In some embodiments, this
configuration may promote adhesion of the lithium metal to an
interleaf layer (e.g., a first interleaf layer, a second interleaf
layer). For example, FIGS. 5A-5G depict a system for cutting a
layer of lithium metal 500, comprising two asymmetric blades.
Referring specifically to FIG. 5A, the system for cutting a layer
of lithium metal comprises a layer of lithium metal 505 positioned
adjacent to substrate 530 and in between first interleaf layer 520
and second interleaf layer 525. Arrow 542 marks an upstream
position, while arrow 544 marks a downstream position of the
system. A first asymmetric blade 510 comprises a steep edge of the
first blade 512 with corresponding first angle 513A and a less
steep edge with corresponding second angle 513B. The first
asymmetric blade may move towards the substrate 530 along a
longitudinal axis 540. A second asymmetric blade 511 comprises a
steep edge of the second blade 514 with corresponding third angle
515A and less steep edge with corresponding fourth angle 515B. The
asymmetric blade 511 may move towards the substrate along
longitudinal axis 541. As shown illustratively in the figure, in
some embodiments, the first angle 513A and the third angle 515A are
identical. In some embodiments, the second angle 513B and the
fourth angle 515B are identical. It should be appreciated that the
first, second, third, and/or fourth angles shown in FIGS. 5A-5G may
have any suitable values and/or ranges as described herein for such
angles. The first asymmetric blade may be located closer to an
upstream position, while the second asymmetric blade may be located
closer to a downstream position. As pictured in the figure, the two
asymmetric blades may be identical, but one blade may be reversed
such that the steep edges face towards each other. That is to say,
in FIG. 5A, for example, the steep edge of first blade 512 faces
the steep edge of second blade 514.
[0041] As shown illustratively in FIG. 5B, the first asymmetric
blade 510 may be moved towards the substrate along perpendicular
longitudinal axis 540 and may cut (e.g., crush cut) the layer of
lithium metal, cutting the layer of lithium metal into lithium
metal piece 505A and 505B. The second asymmetric blade 511 may then
move towards the substrate along perpendicular longitudinal axis
541 and cut lithium metal piece 505A into lithium metal piece 505C
and 505D, as shown illustratively in FIG. 5C. The asymmetric blades
may be lifted and the lithium metal pieces (e.g., 505B, 505C, 505D)
may be moved further downstream, shown illustratively in FIG. 5D.
Alternatively, if asymmetric blades are a part of a common die or
are otherwise integrally connected to one another, they may move
towards the substrate and may cut the lithium metal
simultaneously.
[0042] In some embodiments, the first interleaf layer may be
removed from the layer of lithium metal (e.g., one or more lithium
metal pieces). Referring now to FIGS. 5E-5F, the first interleaf
layer 520 may be removed from lithium metal piece 505D and/or
lithium metal piece 505C. In some embodiments, a lithium metal
piece (e.g., lithium metal piece 505D in FIGS. 5C-5F) may not have
the desired geometry (e.g., and may be designated as waste lithium)
and may be removed from the system. An example of removal is shown
in FIG. 5G. In some embodiments, a cut piece of lithium metal may
have identical cut edges (e.g., edges with the same steepness),
e.g., around the perimeter of the cut piece. For example, in FIG.
5G, cut lithium metal 505C has cut edges that match the steep edge
of first blade 512 and the steep edge of second blade 514 in FIG.
5A. In some embodiments, cut lithium piece (e.g., lithium metal
piece 505C in FIG. 5G) may be used as part of a lithium metal
electrode in an electrochemical cell.
[0043] In some embodiments, an electrode assembly or composite
electrode may be positioned between the first interleaf layer and
the second interleaf layer, and the asymmetric blades described
herein may be used to cut not only the electroactive material layer
(e.g., lithium metal layer), but also any layers adjacent to the
electroactive material layer as part of a stacked assembly. As
shown in the illustrative embodiment of FIG. 6A, an electrode
assembly 610 includes several layers that are stacked together to
form an electrode 612 (e.g., a lithium electrode, an anode, a
cathode). For example, electrode 612 may be formed by optionally
positioning or depositing one or more release layers 624 on a
surface of the second interleaf layer 125, which is adjacent
substrate 130 in the figure. As described in more detail below, the
release layer serves to subsequently release the electrode from the
substrate so that it is not incorporated into the final
electrochemical cell. To form the electrode, an electrode component
such as a current collector 626 can be positioned or deposited
adjacent the release layer and the release layer can be positioned
adjacent to the second interleaf layer 125 and/or the substrate.
Subsequently, an electroactive material layer 628 (e.g., lithium
metal layer) may be positioned or deposited adjacent to current
collector 626. In this embodiment, surface 629 of the electroactive
layer may be positioned adjacent to the first interleaf layer,
while the release layer 624 may be positioned adjacent to the
second interleaf and/or the substrate. In this arrangement, the
asymmetric blade may cut assembly 612, which includes electroactive
layer 628 (e.g., a lithium metal layer). In some embodiments, the
first interleaf layer is a battery separator material such that
cutting the electroactive layer also results in cutting at least
the first interleaf layer, resulting in an electrode assembly that
may be suitable for an electrochemical cell or a battery. It should
be appreciated that while a release layer is shown in FIG. 6A, in
some embodiments it may be absent from the stacked assembly.
[0044] After electrode assembly 610 has been formed, the substrate
130 may be released from the electrode through the use of release
layer 624. Release layer 624 can be either released along with the
substrate so that the release layer is not a part of the final
electrode structure, or the release layer may remain a part of the
final electrode structure.
[0045] The positioning of the release layer during release of the
substrate can be varied by tailoring the chemical and/or physical
properties of the release layer. For example, if it is desirable
for the release layer to be part of the final electrode structure,
the release layer may be tailored to have a greater adhesive
affinity to current collector 626A relative to its adhesive
affinity to carrier substrate 620. On the other hand, if it is
desirable for the release layer to not be part of an electrode
structure, the release layer may be designed to have a greater
adhesive affinity to substrate 130 relative to its adhesive
affinity to current collector 626. In the latter case, when a
peeling force is applied to carrier substrate 620 (and/or to the
electrode), the release layer is released from current collector
626 and remains on substrate 130. In some embodiments, the first
interleaf layer 120 may be removed from assembly 610 before or
after cutting. In some embodiments, the electrode assembly 612 is
fabricated first and then positioned between first and second
interleaf layers to be cut by an asymmetric blade as described
herein.
[0046] In some embodiments, a substrate, release layer, and a
current collector may be received in a roll form. The electroactive
layer (e.g., the lithium metal layer) may be deposited onto the
current collector, together with any optional protective layers.
The release layer, current collector, electroactive layer (e.g.,
lithium metal layer), and optional protective layer may then be
released from the substrate. In some embodiments, the release layer
remains on the stacked assembly (e.g., on the current collector);
however, in other embodiments, the release layer remains on the
substrate. The stacked assembly may then be positioned between a
first and second interleaf layer and may be cut using a cutting
system or blade as described herein.
[0047] In some embodiments, substrate 130 is left intact with
electrode 612 as a part of electrode assembly 610 after fabrication
of the electrode, but before the electrode is incorporated into an
electrochemical cell. For instance, electrode assembly 610 may be
packaged and shipped to a manufacturer who may then incorporate
electrode 612 into an electrochemical cell. In such embodiments,
electrode assembly 610 may be inserted into an air and/or a
moisture-tight package to prevent or inhibit deterioration and/or
contamination of one or more components of the electrode assembly.
Allowing the substrate to remain attached to electrode 612 can
facilitate handling and transportation of the electrode. For
instance, the substrate may be relatively thick and have a
relatively high rigidity or stiffness, which can prevent or inhibit
electrode 612 from distorting during handling. In such embodiments,
the carrier substrate can be removed by the manufacturer before,
during, or after assembly of an electrochemical cell.
[0048] Although FIG. 6A shows release layer 624 positioned between
substrate 620 and current collector 130, in other embodiments, the
release layer may be positioned between other components of an
electrode. For example, the release layer may be positioned
adjacent to surface 629 of electroactive material layer 628, and
the substrate may be positioned on the opposite side of the
electroactive material layer (not shown). In some such embodiments,
an electrode may be fabricated by first positioning one or more
release layers onto a substrate. Then, if any protective layer(s)
is to be included, the protective layer(s) can be positioned on the
one or more release layers. For example, each layer of a
multi-layered structure may be positioned separately onto a release
layer, or the multi-layered structure may be pre-fabricated and
positioned on a release layer at once. The electroactive material
layer may then be positioned on the multi-layered structure. (Of
course, if a protective layer, such as a multi-layered structure,
is not included in the electrode, the electroactive material layer
can be positioned directly on the release layer.) Afterwards, any
other suitable layers, such as a current collector, may be
positioned on the electroactive material layer. To form the
electrode, the carrier substrate can be removed from the protective
layer(s) (or the electroactive material layer where protective
layers are not used) via the release layer. The release layer may
remain with the electrode or may be released along with the carrier
substrate.
[0049] In some embodiments, a release layer has an adhesive
function of allowing two components of an electrochemical cell to
adhere to one another. One such example is shown in the embodiments
illustrated in FIGS. 6B and 6C. For example, as shown
illustratively in FIG. 6B, a first electrode portion 612A may
include one or more release layers 624A, a current collector 626A,
and an electroactive material layer 628A (e.g., a lithium metal
layer). Such an electrode portion may be formed after being
released from a substrate, e.g., using the method described above
in connection with FIG. 6A. Similarly, a second electrode portion
612B may include a release layer 624B, a current collector 626B,
and an electroactive material layer 628B. Additional layers can
also be deposited onto surfaces 629A and/or 629B of electrode
portions 612A and 612B respectively, as described above. As shown
in FIGS. 6B-6C, first electrode 612A and 612B may both be
positioned between two interleaf layers, such as interleaf layer
120 and interleaf layer 125, and may also be positioned adjacent to
a substrate, such as substrate 130.
[0050] As shown in the embodiment illustrated in FIGS. 6B-6C, a
back-to-back electrode assembly 613, positioned between first
interleaf layer 120 and second interleaf layer 130 may be formed by
joining electrode portions 612A and 612B, e.g., via release layers
624A and 624B. The electrode portions may be separate, independent
units or part of the same unit (e.g., folded over). As illustrated
in FIG. 6C, release layers 624A and 624B are facing one another;
however, other configurations are also possible. The entire
assembly 613 may then be cut with the asymmetric blade. In some
embodiments, the asymmetric blade may cut the first interleaf layer
and/or the second interleaf layer. In some embodiments, the first
interleaf layer may be removed from the assembly.
[0051] In some embodiments, the asymmetric blade may be configured
along one or more cutting edges of a die as to die cut a layer of
lithium metal. A non-limiting example of such a die is depicted in
FIG. 7. The use of a die cut may advantageously facilitate
successive cuts of a layer of lithium metal where the die is formed
in the desired shape (e.g., perimeter) of a lithium electrode, for
example, to use in an electrochemical cell or a battery. In such
embodiments, the asymmetric blade may cut the layer of lithium
metal as to provide an inner portion (e.g., a lithium electrode)
and an outer portion (e.g., the frame). In some embodiments, the
outer portion may be discarded (e.g., lithium waste), while the
inner portion continues downstream and/or is used as a component of
an electrochemical cell or a battery.
[0052] As mentioned above, the asymmetric blade may be used to cut
a layer of lithium metal. An asymmetric blade may comprise a tip, a
first edge, and a second edge. The first edge may extend from the
tip of the blade by a first angle. The first angle may be defined
relative to a longitudinal axis drawn from the tip of the blade
perpendicular to the surface of the substrate as shown from a
cross-section of the blade. An example of first angle defined
relative to the longitudinal axis can be seen in FIG. 1A. In some
embodiments, the first angle (e.g., a smaller angle of an
asymmetric blade) is less than or equal to 25 degrees (e.g., 15
degrees). For example, in some embodiments, the first angle is less
than or equal to 25 degrees, less than or equal to 24 degrees, less
than or equal to 23 degrees, less than or equal to 22 degrees, less
than or equal to 21 degrees, less than or equal to 20 degrees, less
than or equal to 19 degrees, less than or equal to 18 degrees, less
than or equal to 17 degrees, less than or equal to 16 degrees, less
than or equal to 15 degrees, less than or equal to 14 degrees, less
than or equal to 13 degrees, less than or equal to 12 degrees, less
than or equal to 11 degrees, less than or equal to 10 degrees, less
than or equal to 9 degrees, less than or equal to 8 degrees, less
than or equal to 7 degrees, less than or equal to 6 degrees, less
than or equal to 5 degrees, less than or equal to 4 degrees, less
than or equal to 3 degrees, less than or equal to 2 degrees, less
than or equal to 1 degree, or 0 degrees. In some embodiments, the
first angle is greater than or equal to 0 degrees, greater than or
equal to 1 degree, greater than or equal to 2 degrees, greater than
or equal to 3 degrees, greater than or equal to 4 degrees, greater
than or equal to 5 degrees, greater than or equal to 6 degrees,
greater than or equal to 7 degrees, greater than or equal to 8
degrees, greater than or equal to 9 degrees, greater than or equal
to 10 degrees, greater than or equal to 11 degrees, greater than or
equal to 12 degrees, greater than or equal to 13 degrees, greater
than or equal to 14 degrees, greater than or equal to 15 degrees,
greater than or equal to 16 degrees, greater than or equal to 17
degrees, greater than or equal to 18 degrees, greater than or equal
to 19 degrees, greater than or equal to 20 degrees, greater than or
equal to 21 degrees, greater than or equal to 22 degrees, greater
than or equal to 23 degrees, greater than or equal to 24 degrees,
or greater than or equal to 25 degrees. Combinations of the
above-referenced ranges are also possible (e.g., greater than or
equal to 0 degrees and less than or equal to 25 degrees). Other
ranges are also possible.
[0053] Similarly, a second edge may have a second angle defined
relative to the longitudinal axis, an example of which is
illustrated in FIG. 1A. In some embodiments, the second angle
(e.g., the larger angle of an asymmetric blade) is less than or
equal to 70 degrees (e.g., 55 degrees). In some embodiments, the
second angle is less than or equal to 70 degrees, less than or
equal to 65 degrees, less than or equal to 60 degrees, less than or
equal to 55 degrees, less than or equal to 50 degrees, less than or
equal to 45 degrees, less than or equal to 40 degrees, less than or
equal to 35 degrees, less than or equal to 30 degrees, less than or
equal to 25 degrees, less than or equal to 20 degrees, less than or
equal to 15 degrees, less than or equal to 10 degrees, or less than
or equal to 5 degrees. In some embodiments, the second angle is
greater than or equal to 5 degrees, greater than or equal to 10
degrees, greater than or equal to 15 degrees, greater than or equal
to 20 degrees, greater than or equal to 25 degrees, greater than or
equal to 30 degrees, greater than or equal to 35 degrees, greater
than or equal to 40 degrees, greater than or equal to 45 degrees,
greater than or equal to 50 degrees, greater than or equal to 55
degrees, greater than or equal to 60 degrees, greater than or equal
to 65 degrees, or greater than or equal to 70 degrees. Combinations
of the above-referenced ranges are also possible (e.g., greater
than or equal to 30 degrees and less than or equal to 70 degrees).
Other ranges are also possible.
[0054] The first angle and the second angle may be separated by a
longitudinal axis that passes through the tip of the blade. In some
embodiments, the first angle and the second angle have a sum
greater than or equal to 50 degrees and/or less than or equal to 75
degrees (e.g., 55 degrees). In some embodiments, the first angle
and the second angle have a sum greater than or equal to 50
degrees, greater than or equal to 55 degrees, greater than or equal
to 60 degrees, greater than or equal to 65 degrees, greater than or
equal to 70 degrees, or greater than or equal to 75 degrees. In
some embodiments, the first angle and the second angle have a sum
less than or equal to 75 degrees, less than or equal to 70 degrees,
less than or equal to 65 degrees, less than or equal to 60 degrees,
less than or equal to 55 degrees, or less than or equal to 50
degrees. Combinations of the above-referenced ranges are also
possible (e.g., greater than or equal to 55 degrees and less than
or equal to 70 degrees). Other ranges are also possible.
[0055] While in some embodiments the asymmetric blade may have one
tip, with a first side and a second side, in other embodiments, an
additional tip (e.g., a second tip) is present. In some cases, the
asymmetric blade may comprise two or more tips, with the second tip
having a third side and a fourth side. FIG. 2C illustrates a blade
having more than one tip. The use of more than one tip may
advantageously provide a configuration where a layer (e.g., lithium
metal, the first interleaf layer, the second interleaf layer) can
be cut from multiple locations on the lithium metal, such as in a
die cut.
[0056] In embodiments in which an asymmetric blade or a die (which
may include more than one asymmetric blade) includes more than one
tip, the blade or die may include a third side and a fourth side,
and a third angle and fourth angle. In some embodiments, the third
angle is less than or equal to 25 degrees, less than or equal to 24
degrees, less than or equal to 23 degrees, less than or equal to 22
degrees, less than or equal to 21 degrees, less than or equal to 20
degrees, less than or equal to 19 degrees, less than or equal to 18
degrees, less than or equal to 17 degrees, less than or equal to 16
degrees, less than or equal to 15 degrees, less than or equal to 14
degrees, less than or equal to 13 degrees, less than or equal to 12
degrees, less than or equal to 11 degrees, less than or equal to 10
degrees, less than or equal to 9 degrees, less than or equal to 8
degrees, less than or equal to 7 degrees, less than or equal to 6
degrees, less than or equal to 5 degrees, less than or equal to 4
degrees, less than or equal to 3 degrees, less than or equal to 2
degrees, less than or equal to 1 degree, or 0 degrees. In some
embodiments, the third angle is greater than or equal to 0 degrees,
greater than or equal to 1 degree, greater than or equal to 2
degrees, greater than or equal to 3 degrees, greater than or equal
to 4 degrees, greater than or equal to 5 degrees, greater than or
equal to 6 degrees, greater than or equal to 7 degrees, greater
than or equal to 8 degrees, greater than or equal to 9 degrees,
greater than or equal to 10 degrees, greater than or equal to 11
degrees, greater than or equal to 12 degrees, greater than or equal
to 13 degrees, greater than or equal to 14 degrees, greater than or
equal to 15 degrees, greater than or equal to 16 degrees, greater
than or equal to 17 degrees, greater than or equal to 18 degrees,
greater than or equal to 19 degrees, greater than or equal to 20
degrees, greater than or equal to 21 degrees, greater than or equal
to 22 degrees, greater than or equal to 23 degrees, greater than or
equal to 24 degrees, or greater than or equal to 25 degrees.
Combinations of the above-referenced ranges are also possible
(e.g., greater than or equal to 0 degrees and less than or equal to
25 degrees). Other ranges are also possible.
[0057] In some embodiments, the fourth angle is less than or equal
to 70 degrees, less than or equal to 65 degrees, less than or equal
to 60 degrees, less than or equal to 55 degrees, less than or equal
to 50 degrees, less than or equal to 45 degrees, less than or equal
to 40 degrees, less than or equal to 35 degrees, less than or equal
to 30 degrees, less than or equal to 25 degrees, less than or equal
to 20 degrees, less than or equal to 15, less than or equal to 10
degrees, or less than or equal to 5 degrees. In some embodiments,
the fourth angle is greater than or equal to 5 degrees, greater
than or equal to 10 degrees, greater than or equal to 15 degrees,
greater than or equal to 20 degrees, greater than or equal to 25,
greater than or equal to 30 degrees, greater than or equal to 35,
greater than or equal to 40 degrees, greater than or equal to 45
degrees, greater than or equal to 50 degrees, greater than or equal
to 55 degrees, greater than or equal to 60 degrees, greater than or
equal to 65 degrees, or greater than or equal to 70 degrees.
Combinations of the above-referenced ranges are also possible
(e.g., greater than or equal to 30 degrees and less than or equal
to 70 degrees). Other ranges are also possible.
[0058] The third angle and the fourth angle may be separated by a
longitudinal axis that passes through the second tip. In some
embodiments, the third angle and the fourth angle have a sum
greater than or equal to 50 degrees and less than or equal to 75
degrees (e.g., 55 degrees). In some embodiments, the first angle
and the second angle have a sum greater than or equal to 50
degrees, greater than or equal to 55 degrees, greater than or equal
to 60 degrees, greater than or equal to 65 degrees, greater than or
equal to 70 degrees, or greater than or equal to 75 degrees. In
some embodiments, the third angle and the fourth angle have a sum
less than or equal to 75 degrees, less than or equal to 70 degrees,
less than or equal to 65 degrees, less than or equal to 60 degrees,
less than or equal to 55 degrees, or less than or equal to 50
degrees. Combinations of the above-referenced ranges are also
possible (e.g., greater than or equal to 55 degrees and less than
or equal to 70 degrees). Other ranges are also possible.
[0059] The asymmetric blade described herein may have a surface
roughness, e.g., a root mean square (RMS) surface roughness, of
less than or equal to 1 micron and greater than or equal to 0.5 nm.
In some embodiments, a layer has an RMS surface roughness of less
than or equal to 1 micron, less than or equal to 500 nm, less than
or equal to 100 nm, less than or equal to 50 nm, less than or equal
to 25 nm, less than or equal to 10 nm, less than or equal to 5 nm,
less than or equal to 1 nm, or less than or equal to 0.5 nm. In
some embodiments, a asymmetric blade has an RMS surface roughness
of greater than or equal to 0.5 nm, greater than or equal to 1 nm,
greater than or equal to 5 nm, greater than or equal to 10 nm,
greater than or equal to 25 nm, greater than or equal to 50 nm,
greater than or equal to 100 nm, greater than or equal to 500 nm,
or greater than or equal to 1 micron. Combinations of the
above-referenced range are also possible (e.g. less than or equal
to 1 micron and greater than or equal to 0.5 nm). Other ranges are
also possible.
[0060] In some embodiments, the asymmetric blade is used to cut
lithium metal (e.g., a layer of lithium metal). As described above,
the lithium metal may be obtained as a solid immersed in oil, or as
a foil. It may also be possible to deposit lithium metal onto a
surface using a variety of techniques, including vacuum deposition
or chemical vapor deposition. Those of ordinary skill in the art
will be capable of selecting an appropriate source of lithium
metal. Systems and methods described herein may be suitable for
other soft metals, such as alkali metals (e.g., Li, Na, K, Cs,
etc.).
[0061] The thickness of the lithium metal may be selected depending
on the size desired, for example, for an electrode in a battery,
but generally may be selected to be thick enough to form an
electrode, but thin enough to be cut by the asymmetric blade. In
some embodiments, a thickness of the lithium metal layer is greater
than or equal to 0.5 microns, greater than or equal to 1 micron,
greater than or equal to 5 microns, greater than or equal to 10
microns, greater than or equal to 15 microns, greater than or equal
to 20 microns, greater than or equal to 25 microns, greater than or
equal to 30 microns, greater than or equal to 40 microns, greater
than or equal to 50 microns, greater than or equal to 60 microns,
greater than or equal to 70 microns, greater than or equal to 80
microns, greater than or equal to 90 microns, greater than or equal
to 100 microns, greater than or equal to 250 microns, greater than
or equal to 500 microns, or greater than or equal to 1000 microns.
In some embodiments, a thickness of the lithium metal layer is less
than or equal to 1000 microns, less than or equal to 500 microns,
less than or equal to 250 microns, less than or equal to 100
microns, less than or equal to 90 microns, less than or equal to 80
microns, less than or equal to 70 microns, less than or equal to 60
microns, less than or equal to 50 microns, less than or equal to 40
microns, less than or equal to 30 microns, less than or equal to 25
microns, less than or equal to 20 microns, less than or equal to 15
microns, less than or equal to 10 microns, less than or equal to 5
microns, less than or equal to 1 micron, or less than or equal to
0.5 microns. Combinations of the above-referenced ranges are also
possible (e.g., greater than or equal to 0.5 microns and less than
or equal to 20 microns, greater than or equal to 10 microns and
less than or equal to 50 microns). Other ranges are also
possible.
[0062] In some embodiments, the layer of lithium metal has a low
surface roughness, e.g., a root mean square (RMS) surface roughness
of less than 1 micron, less than 500 nm, less than about 100 nm,
less than about 50 nm, less than 25 nm, less than 10 nm, less than
5 nm, less than 1 nm, or less than 0.5 nm. Smooth lithium metal
layers can be achieved, in some embodiments, by controlling vacuum
deposition of the lithium metal layers. The lithium metal layer may
be deposited onto a smooth surface (e.g., a smooth current
collector layer) having the same or a similar RMS surface roughness
as the desired lithium metal layer. Such and other methods can
produce lithium metal layer(s) that are at least 1.5.times.,
2.times., 3.times., 4.times., 5.times., or even 10.times. smoother
than certain commercially-available foils, resulting in
substantially uniformly-smooth surfaces.
[0063] As mentioned above and elsewhere herein, in some
embodiments, an optional protective layer may be present. This
optional protective layer may be adjacent to the layer of lithium
metal. The optional protective layer(s) may be made from any
suitable material capable of acting as a protective layer for the
underlying electrode structure (e.g., a lithium metal layer) and
that is conductive to the electroactive species. The protective
layer may also be referred to as a "single-ion conductive material
layer." In some embodiments, the protective layer is a solid. In
some embodiments, the protective layer comprises or may be
substantially formed of a non-polymeric material. For example, the
protective layer may comprise or may be substantially formed of an
inorganic material. Depending on the particular embodiment, the
protective layer may be either electrically insulating or
electrically conducting. In some embodiments, the protective layer
is a ceramic, a glassy-ceramic, or a glass. Additional suitable
materials for the protective layer may include, but are not limited
to, lithium nitride, lithium silicate, lithium borate, lithium
aluminate, lithium phosphate, lithium phosphorus oxynitride,
lithium silicosulfide, lithium germanosulfide, lithium oxides
(e.g., Li.sub.2O, LiO, LiO.sub.2, LiRO.sub.2, where R is a rare
earth metal), lithium lanthanum oxides, lithium titanium oxides,
lithium borosulfide, lithium aluminosulfide, lithium
phosphosulfide, and combinations thereof.
[0064] A protective layer may be deposited by any suitable method
such as sputtering, electron beam evaporation, vacuum thermal
evaporation, laser ablation, chemical vapor deposition (CVD),
thermal evaporation, plasma enhanced chemical vacuum deposition
(PECVD), laser enhanced chemical vapor deposition, aerosol
deposition, and jet vapor deposition. The technique used may depend
on the type of material being deposited, the thickness of the
layer, etc.
[0065] In some embodiments, a protective layer that includes some
porosity can be treated with a polymer or other material such that
the pores (e.g., nanopores) of the protective layer may be filled
with the polymer. Examples of techniques for forming such
structures are described in more detail in U.S. patent application
Ser. No. 12/862,528, filed on Aug. 24, 2010, published as U.S. Pub.
No. 2011/0177398, entitled "Electrochemical Cell", which is
incorporated herein by reference in its entirety for all
purposes.
[0066] Additionally or alternatively, in some embodiments, the
protective layer may be a polymer layer that is conductive to the
electroactive species. Suitable polymers include, but are not
limited to, both electrically conducting and electrically
insulating ion conduction polymers. Possible electrically
conducting polymers include, but are not limited to,
poly(acetylene)s, poly(pyrrole)s, poly(thiophene)s, poly(aniline)s,
poly(fluorene)s, polynaphthalenes, poly(p-phenylene sulfide)s, and
poly(para-phenylene vinylene)s. Possible electrically insulating
polymers include, but are not limited to, acrylate,
polyethyleneoxide, silicones, and polyvinylchlorides. Polymers
described herein for release layers can also be used in a
protective layer. In some such embodiments, the polymer(s) is
present in a non-swollen state (e.g., as a thin film), such as in
configurations in which the protective layer comprising the polymer
is separated from the electrolyte by a ceramic, glass or
glassy-ceramic layer. The above polymers may be doped with ion
conducting salts to provide, or enhance, the desired ion conducting
properties. Appropriate salts for lithium based cells include, for
example, LiSCN, LiBr, LiI, LiClO.sub.4, LiAsF.sub.6,
LiSO.sub.3CF.sub.3, LiSO.sub.3CH.sub.3, LiBF.sub.4, LiB(Ph).sub.4,
LiPF.sub.6, LiC(SO.sub.2CF.sub.3).sub.3, and
LiN(SO.sub.2CF.sub.3).sub.2 though other salts may be used for
other chemistries. The above materials may be deposited using spin
casting, doctor blading, flash evaporation, or any other
appropriate deposition technique. In some embodiments, a protective
layer is formed of, or includes, a suitable polymeric material
listed herein for the release layer, optionally with modified
molecular weight, cross-linking density, and/or addition of
additives or other components. In embodiments in which more than
one protective layer is present, each protective layer may each
independently comprise one or more of the above-referenced
materials.
[0067] In some embodiments, the thickness of the protective layer
may be less than or equal to 5 .mu.m, less than or equal to 2
.mu.m, less than or equal to 1.5 .mu.m, less than or equal to 1.4
.mu.m, less than or equal to 1.3 .mu.m, less than or equal to 1.2
.mu.m, less than or equal to 1.1 .mu.m, less than or equal to 1
.mu.m, less than or equal to 0.9 .mu.m, less than or equal to 0.8
.mu.m, less than or equal to 0.7 .mu.m, less than or equal to 0.6
.mu.m, less than or equal to 0.5 .mu.m, less than or equal to 0.4
.mu.m, less than or equal to 0.3 .mu.m, less than or equal to 0.2
.mu.m, less than or equal to 0.1 .mu.m, less than or equal to 50
nm, less than or equal to 30 nm, or any other appropriate
thickness. Correspondingly, the thickness of the protective layer
may be greater than or equal to 10 nm, greater than or equal to 30
nm, greater than or equal to 50 nm, greater than or equal to 0.1
.mu.m, greater than or equal to 0.2 .mu.m, greater than or equal to
0.3 .mu.m, greater than or equal to 0.4 .mu.m, greater than or
equal to 0.6 .mu.m, greater than or equal to 0.8 .mu.m, greater
than or equal to 1 .mu.m, greater than or equal to 1.2 .mu.m,
greater than or equal to 1.4 .mu.m, greater than or equal to 1.5
.mu.m, or any other appropriate thickness. Combinations of the
above are possible (e.g., a thickness of the protective layer may
be less than or equal to 2 .mu.m and greater than or equal to 0.1
.mu.m). Other ranges are also possible. In embodiments in which
more than one protective layer is present, each protective layer
may each independently have a thickness in one or more of the
above-referenced ranges.
[0068] In some embodiments, a portion of a layer (e.g., a
protective layer) and/or a sublayer of a protective layer may be
deposited by an aerosol deposition process. Aerosol deposition
processes are known in the art and generally comprise depositing
(e.g., spraying) particles (e.g., inorganic particles, polymeric
particles) at a relatively high velocity on a surface. Aerosol
deposition, as described herein, generally results in the collision
and/or elastic deformation of at least some of the plurality of
particles. In some aspects, aerosol deposition can be carried out
under conditions (e.g., using a velocity) sufficient to cause
fusion of at least some of the plurality of particles to at least
another portion of the plurality of particles. For example, in some
embodiments, a plurality of particles is deposited on an
electroactive material (and/or any sublayer(s) disposed thereon) at
a relative high velocity such that at least a portion of the
plurality of particles fuse (e.g., forming the portion and/or
sublayer of the protective layer). The velocity required for
particle fusion may depend on factors such as the material
composition of the particles, the size of the particles, the
Young's elastic modulus of the particles, and/or the yield strength
of the particles or material forming the particles.
[0069] In some embodiments, the average ionic conductivity (e.g.,
lithium ion conductivity) of the protective layer is at least
10.sup.-7 S/cm, at least 10.sup.-6 S/cm, at least 10.sup.-5 S/cm,
at least about 10.sup.4 S/cm, at least 10.sup.-3 S/cm, at least
10.sup.-2 S/cm, at least 10.sup.-1 S/cm, at least 1 S/cm, or at
least 10 S/cm. The average ionic conductivity may less than or
equal to 20 S/cm, less than or equal to 10 S/cm, or less than or
equal to 1 S/cm. Conductivity may be measured at room temperature
(e.g., 25 degrees Celsius). In embodiments in which more than one
protective layer is present, each protective layer may each
independently have an ionic conductivity in one or more of the
above-referenced ranges.
[0070] While a single protective layer has been depicted in the
figures, embodiments in which multiple protective layers, or a
multilayer protective layer, are used are also envisioned. Possible
multilayer structures can include arrangements of polymer layers
and single ion conductive layers as described in more detail in
U.S. patent application Ser. No. 12/862,528, filed on Aug. 24,
2010, published as U.S. Pub. No. 2011/0177398, entitled
"Electrochemical Cell," which is incorporated herein by reference
in its entirety for all purposes. For example, a multilayer
protective layer may include alternating single-ion conductive
layer(s) and polymer layer(s), in some embodiments. Other examples
and configurations of possible multilayer structures are also
described in more detail in U.S. patent application Ser. No.
11/400,781, filed Apr. 6, 2006, published as U. S. Pub. No.
2007-0221265, and entitled, "Rechargeable Lithium/Water,
Lithium/Air Batteries" to Affinito et al., which is incorporated
herein by reference in its entirety for all purposes.
[0071] A single layer or multilayer protective layer can act as a
superior permeation barrier by decreasing the direct flow of
species to the electroactive material layer, since these species
have a tendency to diffuse through defects or open spaces in the
layers. Consequently, dendrite formation, self-discharge, and loss
of cycle life can be reduced. Another advantage of a protective
layer includes the mechanical properties of the structure. For
example, where both polymer and inorganic layers are present, the
positioning of a polymer layer adjacent an inorganic conductive
layer can decrease the tendency of the inorganic conductive layer
to crack and can increase the barrier properties of the structure.
Thus, these laminates may be more robust towards stress due to
handling during the manufacturing process than structures without
intervening polymer layers. In addition, a multilayer protective
layer can also have an increased tolerance of the volumetric
changes that accompany the migration of lithium back and forth from
the electroactive material layer during the cycles of discharge and
charge of the cell.
[0072] As described above, some embodiments comprise an interleaf
layer (e.g. a first interleaf layer, a second interleaf layer). The
interleaf layer may protect the asymmetric blade from making direct
contact with the lithium metal, acting as a barrier that prevents
excess lithium from accumulating on the asymmetric blade. For some
embodiment, more than one interleaf layer may be provided; for
example, two interleaf layers (e.g. a top interleaf layer, a bottom
interleaf layer) may be provided whereby the top interleaf layer is
positioned adjacent a top surface of the lithium metal layer and
the bottom interleaf layer may be positioned on a bottom surface of
the lithium metal layer, but above the substrate.
[0073] In some case, an interleaf layer (e.g., a second interleaf
layer) may be adhered to the lithium metal by the asymmetric blade,
as described elsewhere herein. Additional interleaf layers may also
be present, e.g., a third interleaf layer or a fourth interleaf
layer. It will be understood that any property used to describe an
interleaf layer (e.g., a first interleaf layer, a second interleaf
layer) may also apply to additional interleaf layers. In some
embodiments, it may be advantageous for a first interleaf layer
(e.g. the top interleaf layer) to have a thickness less than a
thickness of the second interleaf layer (e.g., the bottom interleaf
layer). In such an embodiment, a thinner first interleaf layer may
facilitate cutting the lithium metal layer and/or the first
interleaf layer. However, it is also noted that, in some
embodiments, it may be advantageous for a first interleaf layer
(e.g., the top interleaf layer) to have a thickness greater than a
thickness of a second interleaf layer (e.g., the bottom interleaf
layer). For example, in an embodiment where the first interleaf
layer comprises a battery separator material, the thickness of the
first interleaf layer may be greater than the thickness of the
second interleaf layer in order meet the desires of the battery
separator thickness. Those of ordinary skill in the art will be
capable of selecting interleaf layer thicknesses appropriate for a
particular application based on the teachings of this disclosure,
such as for cutting lithium electrodes for electrochemical cells or
batteries.
[0074] In some embodiments, an interleaf layer (e.g. a first
interleaf layer, a second interleaf layer, a top interleaf layer, a
bottom interleaf layer) may be of a suitable thickness to allow the
lithium metal layer to be cut. For example, in some embodiments a
thickness of the first interleaf layer is greater than or equal to
5 microns, greater than or equal to 10 microns, greater than or
equal to 25 microns, greater than or equal to 50 microns, greater
than or equal to 75 microns, greater than or equal to 100 microns,
greater than or equal to 150 microns, greater than or equal to 200
microns, or greater than or equal to 250 microns. In some
embodiments, a thickness of the first interleaf layer is less than
or equal to 250 microns, less than or equal to 200 microns, less
than or equal to 150 microns, less than or equal to 100 microns,
less than or equal to 75 microns, less than or equal to 50 microns,
less than or equal to 25 microns, less than or equal to 10 microns,
or less than or equal to 5 microns. Combinations of the
above-referenced ranges are also possible (e.g., greater than or
equal to 5 microns and less than or equal to 250 microns). Other
ranges are also possible.
[0075] In some embodiments, the second interleaf layer may have a
thickness greater than or equal to 5 microns, greater than or equal
to 10 microns, greater than or equal to 25 microns, greater than or
equal to 50 microns, greater than or equal to 75 microns, greater
than or equal to 100 microns, greater than or equal to 150 microns,
greater than or equal to 200 microns, or greater than or equal to
250 microns. In some embodiments, the thickness of the second
interleaf layer is less than or equal to 250 microns, less than or
equal to 200 microns, less than or equal to 150 microns, less than
or equal to 100 microns, less than or equal to 75 microns, less
than or equal to 50 microns, less than or equal to 25 microns, less
than or equal to 10 microns, or less than or equal to 5 microns.
Combinations of the above-referenced ranges are also possible
(e.g., greater than or equal to 5 microns and less than or equal to
250 microns). Other ranges are also possible.
[0076] As described above, in some embodiments, a stack or an
electrode assembly (e.g., an optional protective layer, a lithium
metal layer, a current collector, a release layer, etc.) is present
between two interleaf layers (e.g., a first interleaf layer, a
second interleaf layer). In some embodiments, the asymmetric blade
may cut through a stack or an electrode assembly, which may
advantageously be used to cut preform electrodes for batteries. In
some embodiments, a thickness of a stack and/or an electrode
assembly positioned between two interleaf layers is greater than or
equal to 0.5 microns, greater than or equal to 1 micron, greater
than or equal to 5 microns, greater than or equal to 10 microns,
greater than or equal to 15 microns, greater than or equal to 20
microns, greater than or equal to 25 microns, greater than or equal
to 30 microns, greater than or equal to 40 microns, greater than or
equal to 50 microns, greater than or equal to 60 microns, greater
than or equal to 70 microns, greater than or equal to 80 microns,
greater than or equal to 90 microns, greater than or equal to 100
microns, greater than or equal to 200 microns, greater than or
equal to 250 microns, greater than or equal to 500 microns, greater
than or equal to 750 microns, or greater than or equal to 1000
microns. In some embodiments, a thickness of a stack and/or an
electrode assembly positioned between two interleaf layers is less
than or equal to 1000 microns, less than or equal to 750 microns,
less than or equal to 500 microns, less than or equal to 250
microns, less than or equal to 100 microns, less than or equal to
90 microns, less than or equal to 80 microns, less than or equal to
70 microns, less than or equal to 60 microns, less than or equal to
50 microns, less than or equal to 40 microns, less than or equal to
30 microns, less than or equal to 25 microns, less than or equal to
20 microns, less than or equal to 15 microns, or less than or equal
to 10 microns. Combinations of the above-referenced ranges are also
possible (e.g., greater than or equal to 0.5 microns and less than
or equal to 20 microns). Other ranges are also possible.
[0077] In some embodiments, the thickness of an interleaf layer
(e.g., a first interleaf layer, a second interleaf layer, a top
interleaf layer, a bottom interleaf layer) may be selected to have
a ratio relative to a thickness of a lithium metal layer. In some
embodiments, the ratio of a thickness of an interleaf layer (e.g.,
a first interleaf layer, a second interleaf layer, a top interleaf
layer, a bottom interleaf layer) to thickness of a lithium metal
layer is less than or equal to 10:1, less than or equal to 7:1,
less than or equal to 5:1, less than or equal to 4:1, less than or
equal to 3:1, less than or equal 2:1, or less than or equal to 1:1.
In some embodiments, the ratio of a thickness of an interleaf layer
(e.g., a first interleaf layer, a second interleaf layer, a top
interleaf layer, a bottom interleaf layer) to a thickness of a
lithium metal layer is greater than or equal to 1:1, greater than
or equal to 2:1, greater than or equal to 3:1, greater than or
equal to 4:1, greater than or equal to 5:1, greater than or equal
to 7:1, or greater than or equal to 10:1. Combinations of the
above-referenced ranges are possible (e.g., greater than or equal
to 1:1 and less than or equal to 5:1). Other ranges are also
possible.
[0078] In some embodiments, the asymmetric blade penetrates a layer
of lithium metal so as to crush cut the lithium metal. In some
embodiments, the first interleaf layer may contact (e.g., lightly
touch) a second interleaf layer when the asymmetric blade cuts the
layer of lithium metal. In some embodiments, the first interleaf
layer (e.g., top interleaf layer) is not cut during this process,
while the lithium metal is crush cut. However, in other
embodiments, the first interleaf layer is cut, in addition to the
lithium metal layer being crush cut. In some embodiments, a depth
of penetration of the asymmetric blade relative to the layer of
lithium metal and/or the first interleaf layer may advantageously
contribute in determining if the first interleaf layer is cut.
Those skilled in the art will be capable of determining an
appropriate depth of penetration of the asymmetric blade in cutting
or not cutting through the first interleaf based on systems and
methods described herein.
[0079] By way of example and not limitation, the asymmetric blade
may penetrate (e.g., cut) the first interleaf layer (e.g., top
interleaf layer) by greater than or equal to 5% of a thickness of
the first interleaf layer, greater than or equal to 10% of a
thickness of the first interleaf layer, greater than or equal to
20% of the thickness of the first interleaf layer, greater than or
equal to 40% of a thickness of the first interleaf layer, greater
than or equal to 60% of a thickness of the first interleaf layer,
greater than or equal to 80% of a thickness of the first interleaf
layer, greater than or equal to 90% of a thickness of the first
interleaf layer, greater than or equal to 95% of a thickness of the
first interleaf layer, greater than or equal to 99% of a thickness
of the first interleaf layer, or 100% of a thickness of the first
interleaf layer. In some embodiments, the asymmetric blade may
penetrate (e.g., cut) the first interleaf layer (e.g., top
interleaf layer) by less than or equal to 100% of a thickness of
the first interleaf layer, less than or equal to 99% of a thickness
of the first interleaf layer, less than or equal to 95% of a
thickness of the first interleaf layer, less than or equal to 90%
of a thickness of the first interleaf layer, less than or equal to
80% of a thickness of the first interleaf layer, less than or equal
to 60% of a thickness of the first interleaf layer, less than or
equal to 40% of a thickness of the first interleaf layer, less than
or equal to 20% of a thickness of the first interleaf layer, less
than or equal to 10% of a thickness of the first interleaf layer,
or less than or equal to 5% of a thickness of the first interleaf
layer. Combinations of the above-referenced ranges are also
possible (e.g., greater than or equal to 5% of a thickness of the
first interleaf layer and less than or equal to 80% of a thickness
of the first interleaf layer). Other ranges are possible.
[0080] In some embodiments, the asymmetric blade touches the second
interleaf layer (e.g., bottom interleaf layer), or may stop before
touching the second interleaf layer, but does not cut the second
layer during the cutting process.
[0081] An interleaf layer (e.g., a first interleaf layer, a second
interleaf layer, a top interleaf layer, a bottom interleaf layer)
may comprise a polymer. In some embodiments, the polymer comprises
at least one of polyethylene, polypropylene, TEFLON.RTM., poly
(vinylidene fluoride), polysulfone, polyether sulfone, EVAL.RTM.,
polystyrene, PVOH, poly (vinyl acetate), poly (methyl acrylate),
poly (methyl methacrylate), polyacrylamide, and PET. Other polymers
are possible, as this disclosure is not so limited. In embodiments
in which more than one interleaf layers are present, each interleaf
layer may independently comprise one or more of the
above-referenced polymers.
[0082] In some embodiments, the interleaf layer(s) (e.g., a first
interleaf layer, a second interleaf layer, a top interleaf layer, a
bottom interleaf layer) comprises a battery separator material. In
other words, the interleaf layer may be formed of a material that
can act as a battery separator in an electrochemical cell that
incorporates an electrode or electrode precursor structure
described herein. In some such embodiments, the asymmetric blade
may be configured to cut a first interleaf layer and a second
interleaf layer, in addition to cutting the lithium metal layer.
This may advantageously provide electrode stacks (i.e., a stack
comprising lithium metal and an adjacent battery separator layer,
with optional intervening layers between the lithium metal and the
battery separator layer) that may be used downstream as a component
in an electrochemical cell and/or battery.
[0083] The separator generally comprises a polymeric material
(e.g., polymeric material that does or does not swell upon exposure
to electrolyte). In some embodiments, the separator is located
between the electrolyte and an electrode (e.g., between the
electrolyte and a first electrode, between the electrolyte and a
second electrode, between the electrolyte and an anode, or between
the electrolyte and a cathode).
[0084] The separator can be configured to inhibit (e.g., prevent)
physical contact between two electrodes (e.g., between an anode and
a cathode, between a first electrode and a second electrode), which
could result in short circuiting of the electrochemical cell. The
separator can be configured to be substantially electronically
non-conductive, which can inhibit the degree to which the separator
causes short circuiting of the electrochemical cell. In certain
embodiments, all or portions of the separator can be formed of a
material with a bulk electronic resistivity of at least 10.sup.4,
at least 10.sup.5, at least 10.sup.10, at least 10.sup.15, or at
least 10.sup.20 Ohm-meters. The bulk electronic resistivity may be
measured at room temperature (e.g., 25.degree. C.).
[0085] In some embodiments, the separator can be ionically
conductive, while in other embodiments, the separator is
substantially ionically non-conductive. In some embodiments, the
average ionic conductivity of the separator is at least 10.sup.-7
S/cm, at least 10.sup.-6 S/cm, at least 10.sup.-5 S/cm, at least
10.sup.-4 S/cm, at least 10.sup.-2 S/cm, or at least 10.sup.-1
S/cm. In some embodiments, the average ionic conductivity of the
separator may be less than or equal to 1 S/cm, less than or equal
to 10.sup.-1 S/cm, less than or equal to 10.sup.-2 S/cm, less than
or equal to 10.sup.-3 S/cm, less than or equal to 10.sup.-4 S/cm,
less than or equal to 10.sup.-5 S/cm, less than or equal to
10.sup.-6 S/cm, less than or equal to 10.sup.-7 S/cm, or less than
or equal to 10.sup.-8 S/cm. Combinations of the above-referenced
ranges are also possible (e.g., an average ionic conductivity of at
least 10.sup.-8 S/cm and less than or equal to 10.sup.-1 S/cm).
Other values of ionic conductivity are also possible.
[0086] The average ionic conductivity of the separator can be
determined by employing a conductivity bridge (i.e., an impedance
measuring circuit) to measure the average resistivity of the
separator at a series of increasing pressures until the average
resistivity of the separator does not change as the pressure is
increased. This value is considered to be the average resistivity
of the separator, and its inverse is considered to be the average
conductivity of the separator. The conductivity bridge may be
operated at 1 kHz. The pressure may be applied to the separator in
500 kg/cm.sup.2 increments by two copper cylinders positioned on
opposite sides of the separator that are capable of applying a
pressure to the separator of at least 3 tons/cm.sup.2. The average
ionic conductivity may be measured at room temperature (e.g.,
25.degree. C.).
[0087] In some embodiments, the separator can be a solid. The
separator may be sufficiently porous such that it allows an
electrolyte solvent to pass through it. In some embodiments, the
separator does not substantially include a solvent (e.g., it may be
unlike a gel that comprises solvent throughout its bulk), except
for solvent that may pass through or reside in the pores of the
separator. In other embodiments, a separator may be in the form of
a gel.
[0088] A separator can comprise a variety of materials. The
separator may comprise one or more polymers (e.g., it may be
polymeric, it may be formed of one or more polymers), and/or may
comprise an inorganic material (e.g., it may be inorganic, it may
be formed of one or more inorganic materials). Examples of suitable
polymeric separator materials include, but are not limited to,
polyolefins (e.g., polyethylenes, poly(butene-1),
poly(n-pentene-2), polypropylene, polytetrafluoroethylene);
polyamines (e.g., poly(ethylene imine) and polypropylene imine
(PPI)); polyamides (e.g., polyamide (Nylon), poly( -caprolactam)
(Nylon 6), poly(hexamethylene adipamide) (Nylon 66)); polyimides
(e.g., polyimide, polynitrile, and
poly(pyromellitimide-1,4-diphenyl ether) (Kapton.RTM.) (NOMEX.RTM.)
(KEVLAR.RTM.)); polyether ether ketone (PEEK); vinyl polymers
(e.g., polyacrylamide, poly(2-vinyl pyridine),
poly(N-vinylpyrrolidone), poly(methylcyanoacrylate),
poly(ethylcyanoacrylate), poly(butylcyanoacrylate),
poly(isobutylcyanoacrylate), poly(vinyl acetate), poly(vinyl
alcohol), poly(vinyl chloride), poly(vinyl fluoride), poly(2-vinyl
pyridine), vinyl polymer, polychlorotrifluoro ethylene, and
poly(isohexylcyanoacrylate)); polyacetals; polyesters (e.g.,
polycarbonate, polybutylene terephthalate, polyhydroxybutyrate);
polyethers (poly(ethylene oxide) (PEO), poly(propylene oxide)
(PPO), poly(tetramethylene oxide) (PTMO)); vinylidene polymers
(e.g., polyisobutylene, poly(methyl styrene),
poly(methylmethacrylate) (PMMA), poly(vinylidene chloride), and
poly(vinylidene fluoride)); polyaramides (e.g.,
poly(imino-1,3-phenylene iminoisophthaloyl) and
poly(imino-1,4-phenylene iminoterephthaloyl)); polyheteroaromatic
compounds (e.g., polybenzimidazole (PBI), polybenzobisoxazole (PBO)
and polybenzobisthiazole (PBT)); polyheterocyclic compounds (e.g.,
polypyrrole); polyurethanes; phenolic polymers (e.g.,
phenol-formaldehyde); polyalkynes (e.g., polyacetylene); polydienes
(e.g., 1,2-polybutadiene, cis or trans-1,4-polybutadiene);
polysiloxanes (e.g., poly(dimethylsiloxane) (PDMS),
poly(diethylsiloxane) (PDES), polydiphenylsiloxane (PDPS), and
polymethylphenylsiloxane (PMPS)); and inorganic polymers (e.g.,
polyphosphazene, polyphosphonate, polysilanes, polysilazanes). In
some embodiments, the polymer may be selected from
poly(n-pentene-2), polypropylene, polytetrafluoroethylene,
polyamides (e.g., polyamide (Nylon), poly( -caprolactam) (Nylon 6),
poly(hexamethylene adipamide) (Nylon 66)), polyimides (e.g.,
polynitrile, and poly(pyromellitimide-1,4-diphenyl ether)
(Kapton.RTM.) (NOMEX.RTM.) (KEVLAR.RTM.)), polyether ether ketone
(PEEK), and combinations thereof.
[0089] In some embodiments, a layer(s) (e.g. a first interleaf
layer, a second interleaf layer, a top interleaf layer, a bottom
interleaf layer) has a surface roughness, e.g., a root mean square
(RMS) surface roughness, of less than or equal to 1 micron and
greater than or equal to 0.5 nm. In some embodiments, a layer has
an RMS surface roughness of less than or equal to 1 micron, less
than or equal to 500 nm, less than or equal to 100 nm, less than or
equal to 50 nm, less than or equal to 25 nm, less than or equal to
10 nm, less than or equal to 5 nm, less than or equal to 1 nm, or
less than or equal to 0.5 nm. In some embodiments, a layer has an
RMS surface roughness of greater than or equal to 0.5 nm, greater
than or equal to 1 nm, greater than or equal to 5 nm, greater than
or equal to 10 nm, greater than or equal to 25 nm, greater than or
equal to 50 nm, greater than or equal to 100 nm, greater than or
equal to 500 nm, or greater than or equal to 1 micron. Combinations
of the above-referenced range are also possible (e.g., less than or
equal to 1 micron and greater than or equal to 0.5 nm). Other
ranges are possible.
[0090] In some embodiments, an interleaf layer and/or a release
layer may include one or more crosslinking agents. A crosslinking
agent is a molecule with a reactive portion(s) designed to interact
with functional groups on the polymer chains in a manner that will
form a crosslinking bond between one or more polymer chains.
Examples of crosslinking agents that can crosslink polymeric
materials used for release layers and/or adhesion promoters
described herein include, but are not limited to:
polyamide-epichlorohydrin (polycup 172); aldehydes (e.g.,
formaldehyde and urea-formaldehyde); dialdehydes (e.g., glyoxal
glutaraldehyde, and hydroxyadipaldehyde); acrylates (e.g., ethylene
glycol diacrylate, di(ethylene glycol) diacrylate, tetra(ethylene
glycol) diacrylate, methacrylates, ethelyne glycol dimethacrylate,
di(ethylene glycol) dimethacrylate, tri(ethylene glycol)
dimethacrylate); amides (e.g., N,N'-methylenebisacrylamide,
N,N'-methylenebisacrylamide,
N,N'-(1,2-dihydroxyethylene)bisacrylamide,
N-(1-hydroxy-2,2-dimethoxyethyl)acrylamide); silanes (e.g.,
methyltrimethoxysilane, methyltriethoxysilane, tetramethoxysilane
(TMOS), tetraethoxysilane (TEOS), tetrapropoxysilane,
methyltris(methylethyldetoxime)silane, methyltris(acetoxime)silane,
methyltris(methylisobutylketoxime)silane,
dimethyldi(methylethyldetoxime)silane,
trimethyl(methylethylketoxime)silane,
vinyltris(methylethylketoxime)silane,
methylvinyldi(mtheylethylketoxime)silane,
methylvinyldi(cyclohexaneoneoxxime)silane,
vinyltris(mtehylisobutylketoxime)silane, methyltriacetoxysilane,
tetraacetoxysilane, and phenyltris(methylethylketoxime)silane);
divinylbenzene; melamine; zirconium ammonium carbonate;
dicyclohexylcarbodiimide/dimethylaminopyridine (DCC/DMAP);
2-chloropyridinium ion; 1-hydroxycyclohexylphenyl ketone;
acetophenon dimethylketal; benzoylmethyl ether; aryl triflourovinyl
ethers; benzocyclobutenes; phenolic resins (e.g., condensates of
phenol with formaldehyde and lower alcohols, such as methanol,
ethanol, butanol, and isobutanol), epoxides; melamine resins (e.g.,
condensates of melamine with formaldehyde and lower alcohols, such
as methanol, ethanol, butanol, and isobutanol); polyisocyanates;
dialdehydes; and other crosslinking agents known to those of
ordinary skill in the art.
[0091] In embodiments including a crosslinked polymeric material
and a crosslinking agent, the weight ratio of the polymeric
material to the crosslinking agent may vary for a variety of
reasons including, but not limited to, the functional-group content
of the polymer, its molecular weight, the reactivity and
functionality of the crosslinking agent, the desired rate of
crosslinking, the degree of stiffness/hardness desired in the
polymeric material, and the temperature at which the crosslinking
reaction may occur. Non-limiting examples of ranges of weight
ratios between the polymeric material and the crosslinking agent
include from 100:1 to 50:1, from 20:1 to 1:1, from 10:1 to 2:1, and
from 8:1 to 4:1.
[0092] The adhesive strength between two layers described herein,
such as between a lithium metal layer and an interleaf layer (e.g.,
a first interleaf layer, a second interleaf layer), between a
protective layer and an interleaf layer (e.g., a first interleaf
layer, a second interleaf layer), between a current collector and
an interleaf layer (e.g., a first interleaf layer, a second
interleaf layer), and/or between an interleaf layer and a
substrate, can be tailored as desired. To determine relative
adhesion strength between two layers, a tape test can be performed.
Briefly, the tape test utilizes pressure-sensitive tape to
qualitatively assess the adhesion between a first layer (e.g., an
interleaf layer) and a second layer (e.g., a lithium metal layer).
In such a test, an X-cut can be made through the first layer to the
second layer. Pressure-sensitive tape can be applied over the cut
area and removed. If the first layer stays on the second layer,
adhesion is good. If the first layer comes off with the strip of
tape, adhesion is poor. The tape test may be performed according to
the standard ASTM D3359-02. In some embodiments, a strength of
adhesion between a first layer (e.g., an interleaf layer) and a
second layer (e.g., a lithium metal layer, a current collector, a
protective layer, a substrate) passes the tape test according to
the standard ASTM D3359-02, meaning the second layer does not
delaminate from the first layer during the test. In some
embodiments, the tape test is performed after the two layers have
been included in a cell, such as a lithium-ion cell or any other
appropriate cell described herein, that has been cycled at least 5
times, at least 10 times, at least 15 times, at least 20 times, at
least 50 times, or at least 100 times, and the two layers pass the
tape test after being removed from the cell (e.g., the first layer
does not delaminate from the second layer during the test).
[0093] The peel test may include measuring the adhesiveness or
force required to remove a first layer (e.g., an interleaf layer)
from a unit area of a surface of a second layer (e.g., a lithium
metal layer), which can be measured in N/m, using a tensile testing
apparatus or another suitable apparatus. Such experiments can
optionally be performed in the presence of a solvent (e.g., an
electrolyte) or other components to determine the influence of the
solvent and/or components on adhesion.
[0094] In some embodiments, the strength of adhesion between two
layers (e.g., a first layer such as an interleaf layer and a second
layer such as a lithium metal layer, a protective layer, a current
collector, a substrate) may range, for example, between 100 N/m to
2000 N/m. In some embodiments, the strength of adhesion may be at
least 50 N/m, at least 100 N/m, at least 200 N/m, at least 350 N/m,
at least 500 N/m, at least 700 N/m, at least 900 N/m, at least 1000
N/m, at least 1200 N/m, at least 1400 N/m, at least 1600 N/m, or at
least 1800 N/m. In some embodiments, the strength of adhesion may
be less than or equal to 2000 N/m, less than or equal to 1500 N/m,
less than or equal to 1000 N/m, less than or equal to 900 N/m, less
than or equal to 700 N/m, less than or equal to 500 N/m, less than
or equal to 350 N/m, less than or equal to 200 N/m, less than or
equal to 100 N/m, or less than or equal to 50 N/m. Combinations of
the above-referenced ranges are also possible (e.g., at least 100
N/m and less than or equal to 700 N/m). Other strengths of adhesion
are also possible.
[0095] In some embodiments, the lithium metal layer may be
deposited using physical vapor deposition, sputtering, chemical
deposition, electrochemical deposition, thermal evaporation, jet
vapor deposition, laser ablation, or any other appropriate method.
In an alternative embodiment, the lithium metal layer is deposited
on a protective layer by bonding the lithium metal layer to the
protective layer. In such an embodiment, a temporary bonding layer
might be deposited onto the protective layer prior to bonding the
lithium metal layer, or the lithium metal layer might bond directly
to the protective layer. In some embodiments, the temporary bonding
layer may form an alloy with the lithium metal layer upon
subsequent cycling of the electrode structure in an electrochemical
cell. For example, silver and/or other metals that can alloy with
lithium can be used in some embodiments. In embodiments in which
the protective layer has already been formed or deposited, it may
be unnecessary to maintain a low surface roughness on the exposed
surface of the lithium metal layer. However, embodiments in which
the surface roughness of lithium metal layer is controlled are also
envisioned.
[0096] In some embodiments in which a release layer is present, the
thickness of the release layer may be between greater than or equal
to 0.001 microns and less than or equal to 50 microns. In some
embodiments, a release layer has a thickness of greater than or
equal to 0.001 microns, greater than or equal to 1 micron, greater
than or equal to 2 microns, greater than or equal to 3 microns,
greater than or equal to 5 microns, greater than or equal to 10
microns, greater than or equal to 20 microns, or greater than or
equal to 50 microns. In some embodiments, the thickness of a
release layer is less than or equal to 50 microns, less than or
equal to 20 microns, less than or equal to 10 microns, less than or
equal to 5 microns, less than or equal to 3 microns, less than or
equal to 2 microns, less than or equal to 1 micron, or less than or
equal to 0.001 microns. Combinations of the above-referenced ranges
are possible (e.g., greater than or equal to 2 microns and less
than or equal to 20 microns). Other ranges are possible. In
embodiments in which more than one release layers are present, each
release layer may independently have a thickness in one or more of
the above-referenced ranges.
[0097] In some embodiments, a release layer comprises a
crosslinkable polymers. Non-limiting examples of crosslinkable
polymers include: polyvinyl alcohol, polyvinylbutryl,
polyvinylpyridyl, polyvinyl pyrrolidone, polyvinyl acetate,
acrylonitrile butadiene styrene (ABS), ethylene-propylene rubbers
(EPDM), EPR, chlorinated polyethylene (CPE), ethelynebisacrylamide
(EBA), acrylates (e.g., alkyl acrylates, glycol acrylates,
polyglycol acrylates, ethylene ethyl acrylate (EEA)), hydrogenated
nitrile butadiene rubber (HNBR), natural rubber, nitrile butadiene
rubber (NBR), certain fluoropolymers, silicone rubber,
polyisoprene, ethylene vinyl acetate (EVA), chlorosulfonyl rubber,
flourinated poly(arylene ether) (FPAE), polyether ketones,
polysulfones, polyether imides, diepoxides, diisocyanates,
diisothiocyanates, formaldehyde resins, amino resins,
polyurethanes, unsaturated polyethers, polyglycol vinyl ethers,
polyglycol divinyl ethers, copolymers thereof, and those described
in U.S. Pat. No. 6,183,901 to Ying et al. of the common assignee
for protective coating layers for separator layers. In embodiments
in which more than one release layers are present, each release
layer may independently comprise one or more of the
above-referenced polymers.
[0098] As described above, lithium metal may be adhered (i.e.,
staked) to an interleaf layer. The degree of adherence, e.g.,
adhesion strength, may be varied depending on the degree of
adhesion desired, and have one or more ranges described herein. In
some embodiments, the asymmetric blade may be configured to
advantageously stake (i.e., adhere with a relatively high adhesive
affinity) an interleaf layer to the lithium metal. By way of
example and not limitation, the asymmetric blade may both cut and
stake (e.g., relatively strongly adhere) a cut piece of lithium
metal to the second interleaf layer (e.g., bottom interleaf layer),
while facilitating relatively easy removal of the first interleaf
layer (e.g., top interleaf layer) from the cut lithium metal. In
other words, the strength of adhesion of the first interleaf layer
(e.g., top interleaf layer) to an electrode component (e.g.,
lithium metal layer, optional protective layer) may be less than
the strength of adhesion of the second interleaf layer (e.g.,
bottom interleaf layer) to the an electrode component (e.g.,
lithium metal layer, current collector). In some embodiments,
staking or adhering the lithium metal to the second interleaf layer
may allow for removal of the first interlayer while the lithium
metal remains staked (i.e., adhered with a relatively high adhesive
affinity) to the second interleaf layer. In some embodiments, the
asymmetric blade may stake (i.e., adhere with a relatively high
adhesive affinity) the lithium metal to the first interleaf layer
and the second interleaf layer. In some embodiment still, the
asymmetric layer may cut the lithium metal without adhering the
first interleaf layer nor the second interleaf layer. The degree of
staking or adhesion between layers may be controlled, in some
embodiments, by choosing the appropriate materials for the
interleaf layer(s) and/or appropriate angles of the edges of the
asymmetric blade. Measurement of the adhesion strength is described
elsewhere herein.
[0099] As described herein, in some embodiments, the angle(s) of
the asymmetric blade may determine, at least in part, if the layer
of lithium metal is adhered to an interleaf (e.g., a second (e.g.,
bottom) interleaf layer). As described above, if the first angle of
the first side or edge is larger (e.g., less steep) than the second
angle of the second side or edge, then the cut edge of the layer of
lithium metal cut with the first side will be relatively less
steep, while the cut edge of the layer of lithium metal cut by the
second will be relatively more steep. In some embodiments, the less
steep cut edge of the layer of lithium metal (e.g., a piece of
lithium metal) will adhere or stake (i.e., adhere with a relatively
high adhesive affinity) to the second (e.g., bottom) interleaf
layer (i.e., will have a relatively high adhesive affinity to the
second interleaf layer). Meanwhile, the more steep cut edge of the
layer of lithium metal with adhere to the first (e.g., top)
interleaf layer with a relatively low adhesive affinity, which may
advantageously promote facile removal of the first interleaf layer
relative to the second interleaf layer. In some embodiments, the
arrangement of the blade may be reversed, such that the cut layer
of lithium metal is staked (i.e., will have a relatively high
adhesive affinity to the second (e.g., bottom) interleaf layer)
and/or may have a relatively high adhesive affinity to the first
(e.g., top) interleaf layer where it is desirable to have the first
interleaf layer adhered to the lithium metal (or a protective layer
on the lithium metal).
[0100] In some embodiments, the first interleaf layer may be
removed from the lithium metal (e.g., a cut piece of lithium metal,
after staking to the second interleaf layer). Removal of the first
interleaf may be accomplished by any suitable method, including by
use of vacuum. In some cases, a cut piece of lithium may be removed
after being cut and moving downstream and after the first interleaf
has been removed from the cut piece of lithium. Removal of the cut
piece of lithium may be accomplished using a vacuum apparatus or
any other suitable method for removing the lithium metal from the
second interleaf layer.
[0101] While several embodiments of the present invention have been
described and illustrated herein, those of ordinary skill in the
art will readily envision a variety of other means and/or
structures for performing the functions and/or obtaining the
results and/or one or more of the advantages described herein, and
each of such variations and/or modifications is deemed to be within
the scope of the present invention. More generally, those skilled
in the art will readily appreciate that all parameters, dimensions,
materials, and configurations described herein are meant to be
exemplary and that the actual parameters, dimensions, materials,
and/or configurations will depend upon the specific application or
applications for which the teachings of the present invention
is/are used. Those skilled in the art will recognize, or be able to
ascertain using no more than routine experimentation, many
equivalents to the specific embodiments of the invention described
herein. It is, therefore, to be understood that the foregoing
embodiments are presented by way of example only and that, within
the scope of the appended claims and equivalents thereto, the
invention may be practiced otherwise than as specifically described
and claimed. The present invention is directed to each individual
feature, system, article, material, and/or method described herein.
In addition, any combination of two or more such features, systems,
articles, materials, and/or methods, if such features, systems,
articles, materials, and/or methods are not mutually inconsistent,
is included within the scope of the present invention.
[0102] The indefinite articles "a" and "an," as used herein in the
specification and in the claims, unless clearly indicated to the
contrary, should be understood to mean "at least one."
[0103] The phrase "and/or," as used herein in the specification and
in the claims, should be understood to mean "either or both" of the
elements so conjoined, i.e., elements that are conjunctively
present in some cases and disjunctively present in other cases.
Other elements may optionally be present other than the elements
specifically identified by the "and/or" clause, whether related or
unrelated to those elements specifically identified unless clearly
indicated to the contrary. Thus, as a non-limiting example, a
reference to "A and/or B," when used in conjunction with open-ended
language such as "comprising" can refer, in one embodiment, to A
without B (optionally including elements other than B); in another
embodiment, to B without A (optionally including elements other
than A); in yet another embodiment, to both A and B (optionally
including other elements); etc.
[0104] As used herein in the specification and in the claims, "or"
should be understood to have the same meaning as "and/or" as
defined above. For example, when separating items in a list, "or"
or "and/or" shall be interpreted as being inclusive, i.e., the
inclusion of at least one, but also including more than one, of a
number or list of elements, and, optionally, additional unlisted
items. Only terms clearly indicated to the contrary, such as "only
one of" or "exactly one of," or, when used in the claims,
"consisting of," will refer to the inclusion of exactly one element
of a number or list of elements. In general, the term "or" as used
herein shall only be interpreted as indicating exclusive
alternatives (i.e. "one or the other but not both") when preceded
by terms of exclusivity, such as "either," "one of," "only one of,"
or "exactly one of." "Consisting essentially of," when used in the
claims, shall have its ordinary meaning as used in the field of
patent law.
[0105] As used herein in the specification and in the claims, the
phrase "at least one," in reference to a list of one or more
elements, should be understood to mean at least one element
selected from any one or more of the elements in the list of
elements, but not necessarily including at least one of each and
every element specifically listed within the list of elements and
not excluding any combinations of elements in the list of elements.
This definition also allows that elements may optionally be present
other than the elements specifically identified within the list of
elements to which the phrase "at least one" refers, whether related
or unrelated to those elements specifically identified. Thus, as a
non-limiting example, "at least one of A and B" (or, equivalently,
"at least one of A or B," or, equivalently "at least one of A
and/or B") can refer, in one embodiment, to at least one,
optionally including more than one, A, with no B present (and
optionally including elements other than B); in another embodiment,
to at least one, optionally including more than one, B, with no A
present (and optionally including elements other than A); in yet
another embodiment, to at least one, optionally including more than
one, A, and at least one, optionally including more than one, B
(and optionally including other elements); etc.
[0106] Some embodiments may be embodied as a method, of which
various examples have been described. The acts performed as part of
the methods may be ordered in any suitable way. Accordingly,
embodiments may be constructed in which acts are performed in an
order different than illustrated, which may include different
(e.g., more or less) acts than those that are described, and/or
that may involve performing some acts simultaneously, even though
the acts are shown as being performed sequentially in the
embodiments specifically described above.
[0107] Use of ordinal terms such as "first," "second," "third,"
etc., in the claims to modify a claim element does not by itself
connote any priority, precedence, or order of one claim element
over another or the temporal order in which acts of a method are
performed, but are used merely as labels to distinguish one claim
element having a certain name from another element having a same
name (but for use of the ordinal term) to distinguish the claim
elements.
[0108] In the claims, as well as in the specification above, all
transitional phrases such as "comprising," "including," "carrying,"
"having," "containing," "involving," "holding," and the like are to
be understood to be open-ended, i.e., to mean including but not
limited to. Only the transitional phrases "consisting of" and
"consisting essentially of" shall be closed or semi-closed
transitional phrases, respectively, as set forth in the United
States Patent Office Manual of Patent Examining Procedures, Section
2111.03.
* * * * *